In an existing liquid crystal display, there is a capacitance between a gate and a source in a Thin Film Transistor (TFT)/Thin Film Field Effect Transistor switch. When the TFT switch is turned off, a voltage at the gate transits to a low level from a high level, but because of the existence of the capacitance between the gate and source, a capacitance coupling effect would pull a voltage at a pixel electrode (that is, a pixel voltage) down, which may deviate from a voltage given by a system, such that a deflection direction of the liquid crystal is affected and a transmittance is changed. Also, because the liquid crystal is driven by a polarity inversion of the voltage, human's eyes would perceive flickers in a picture if there is a difference between the transmittance of the liquid crystal as a positive voltage drives and that as a negative voltage drives, and a long time flicker would causes discomfort to the human's eyes.
In order to settle the problem of flickers in the picture, the prior art adjusts a voltage at a common electrode manually, that is, a compensation for the pixel voltage is achieved by adjusting the voltage value of the common electrode, and in particular, the adjustment is performed manually and real-time by a personal computer, etc, connected to a driving Integrated Circuit (IC). For example, the adjustment on the voltage at the common electrode is performed by changing programs and the like in real-time. Meanwhile, a standard flicker detection device is further required in order to eliminate errors among operators. It can be seen that the current implementing methods not only waste human resource but also have low working efficiency.